Apparatus for directive signaling



n. A. FES'SENDEN.

APPARATUS FOR DIRECTIVE SIGNALING.

' APPLICATION man AUG. 16, 1911.-

1,s55,59s. Patenm 00A. 12, 1 20.

EEG E SIGRZQL CQTEPAilY, 0F PORTLAND,

HALE) A. FESS'ENDEB, OF BROOKLIW, MA-

.assresron. to sustain 'rron TEIMR'E.

eas es;

T 0 all whom .2)? may concern:

Be it known that I, REGINALD DEN, and State of Massachusetts, a cltlzenof the United States, have invented a new and useful Improvement inApparatus for Dlrec tive Signaling, of which the followlng 1s aspecification.

My invention. relates to the transmission and receipt of energy and moreparticularly to signaling and still more part cularly to directionalsignaling, especially the location of submarines and submarine signalingstations and also of aeroplanes.

The object of myinvention is to improve the eiiiciency of the sendingand receiving energy and more especially to improve the efiiciency'ofsignaling and still more to improve the eiliciency of apparatus andmethods for locating submarine slgnalmg stations and submarines. It maybe used on shipboard or otherwise.

The figure accompanying this specification illustrates, partlydiagrammat1cally,ap-

A. FEssEN paratus adapted for carrying out my invention.

In the figure, of the destroyer type and 30, 31 and 32 are thecompartments of the forepeak or 011 tanks of the torpedo destroyer,though they may be fluid containers otherwise located, according tocircumstances.

11 and 12 are sound receiving devices of any suitable kind; for example,microphones or stethoscopes, or electro-magnetlc receivers andpreferably oscillators of the kind described in. United States PatentNo. 1,167,366. I shall hereinafter refer to these, generally speaking,as sound detectors These oscillators are shown as located on board shipand are placed in any suitable position with reference to each other,either side by side, or, as shown, back to back in the same tank oradjacent fluid containing tanks, and preferably have their facesperpendicular to the skin of the ship. As shown, they are separated bythe sound insulating screen l3, 14, of any kind, being attached to eachother and to it by the bolts 15, 16, which may be insulated therefrom bysoft rubber or lead in a known way.

Both oscillators and sound screen are mounted on a pivot 29 and can berotated by any suitable means, as for example, by

the handle 17.

Specification of Letteraratent.

of Brookline, in the county of Norfolk.

83 is a vessel for example' are adjustable inductances.

lF'e/tentediict. 312, i922.

Application filed August 16, 1917." t'lcrial l lo, 1393122.

' The sound screen 13,14, may be con- *structed and shaped in anysuitable way to produce-the desired result; for example, at

the end 14: the sound screen is shown in curved shape so as to shield toa greater extent than at'thefend 13.

I prefer so to shape the sound screen 13,

' 14 that a sound coming from 'a given angle and striking theoscillators will be heard with the same relative intensities and phasesas a sound coming from the same angle and striking the head of a humanbeing.

The shape of the sound screen to accomplish this is best determined byexperiment,- the shape being varied until a person listening in ontelephone receivers attached to the oscillators will obtain'the samechange in relative sound-intensities in the two receivers when theoscillators are turned to a certain angle as he obtains when he turnshishead through thesame angle.

An important point to note. is that when l the oscillators are used in adifl'e'rent medlum from air, for example in water, the distance of theoscillators apart should preferably bear the same relation to thevelocity of sound in such medium, for example water, as the usual'distance; apart of the two ears of a human-body bearsv to the velocityofsound in air. For example, if the distance between the cars is 8 inchesand the velocity of sound in air is 1100 feet per second, then itthe'oscillators are inimersedin water, in which'the velocity of sound is4400 feet per second, the oscillators should preferably be placed alittle less than 13 feet apart. If the oscillators are placed fartherapart, as ,for example, 10 feet, still further changes are obtained andthe sound screen must be extended still farther in order to obtain thedesired efiect on turning the oscillators around on their pivot 29.

18, 19, 20,21are leads from the oscillators to the indicators shown astelephone receivers 26, 27, which with the other apparatus may belocated upon the. bridge or other convenient place and are connected bythe head band 28 but are not electrically con nected to each other.

-33 and 34 are switches for opening or ciosing the lead circuits asdesired.

22, '23 are adjustable capacities, and 2d, 25

'lhese capacitiesand inductances have the function, in

addition to their other functions, that by changing their relativevalues the phase of the sounds reaching the receivers 26, 27, can bealtered without turning the oscillators on their pivot, or, it theoscillators are turned on their pivot, the change of phase may beincreased or decreased.

For example, if a sound is received on the port bow, the oscillators maybe either turned by means of the handle 17 until the sound appears tocome from a point perpendicular to and in front of the line joining thecenters of the diaphragms of the two oscillators, the sound then beingequally loud to both ears of the observer, and the anglethrough: whichthe handle ll"v is being moved may be measured and the exact directionof the sound be thus determined. Or the oscillators-may be leftstationary and the condensers 22, 23, or inductances 24:, 25, or both,adjusted until the sound appears dead ahead and the readings of the soudensers and inductances taken and in this way the exact directiondetermined. Or both oscillators and condensers and inductances may beleft stationary and the vessel turned until the sound appears to come indead ahead and the bow is pointed in the direction of the source ofsound,

The tanks 30, 31, 32 are preferably filled either with water or oil, andwhen the oil is used up, it is preferably replaced with water.

The insertion of the oscillators in fluid filled tanks, for example,forepeak tanks, or, as shown, in oil tanks, has the great advantagethat, as applicant has discovered, it enables the sound to be receivednearly as well dead ahead as abeam.

For exam le, with the installation placed on the S. S. eoereaiuw thedistance at which it was possible to send 'and receive dead ahead was31-1; miles as against 36 miles abeam. With the installation placed onthe U. S. destroyer Ag Zwia the working dis tance dead ahead was 843% ofthat abeam.

l have discovered that it is possible to still further increase therange dead ahead or dead astern by making the skin of the ship or thewall of the tanks or the chamber containing the sound receiver so thatthe index of sound refraction of the skin of the ship or the wall of thetanks relative to water is unity.

For example, the velocity of sound in water is approximately 4400v feetper second, while the velocity of sound in steel is approximatelyll',000 feet per second. Consequently, sounds striking the skin of theship at a small angle are totally reflected and do not enter the shipand aii ect the oscillators. l have found, however, that by loadinn" x"th ship so that the index or a 1,855,&Qt3

attach, lumps or disks or plates of lead or other suitable material,such as tungsten, to the inside of the skin of the ship, or to usematerial such as zinc or tin or tin alloyed with lead, or to use a platehaving holes punched in it, the holes being tilled with lead or brass.Other arrangements may suggest themselves, but whatever the arrangementused, it should be such as to make the index of refraction of the skinof the ship or the wall of the tanks relative to water-equal to unity,and if weights are used, such as disks of lead,'they should be closetogether, i. 6., the distance between any two adjacent ones should beapproximately equal to less than a quarter wave length of the soundwhich is to be received.

This method is also of value as a method of eliminating high pitchedsounds which it is not desired to receive, as sounds whose quarter wavelength is less than the distance between the weights may be retractedwhile sounds of longer wave length will be trans mitted.

Other arrangements of: apparatus to ac complish this result andbe withinthe scope of my invention will occur to those skilled in the art,

What I claim is:

1. The combination of a fluid container,

two sound detectors located in the fluid in said fluid container, asound screen located between said sound detectors, and two indicaters,each connected to one of the sound detectors, said sound screen being"shaped as described whereby it will produce a sound shadow with relationto said detectors similar to that produced by the human head withrelation to the ears.

2. The combination of a fluid container, two sound detectors located inthe fluid in said fluid container, a sound screen located between saidsound detectors, and two indicators, each connected to one of the sounddetectors, said sound screen being proportioned with relation to saiddetectors ap-. proximately as the human head is to the location of theears.

3. The combination of a fluid container, two sound detectors located inthe fluid in said fluid container, and two indicators, each connected toone of the sound detectors, the connections between said detectors andindicators com arising inductances and capacities adaptec to vary thecurrent phase generated by the detectors and received by the -etectorlocated avingits substantially the same as that of the medium outsidethe tank through which the slgnals are sent and received.

5. A tank and a sound detector located the medium through which thedesired sig-- nals are transmitted and received whereby the index ofrefraction of said wall will be made substantially the same as water.

' 6. A tank and a sound detector located therein, a wall ofsaid tankbeing loaded with weights 'separated'from each other by a distanceapproximately less than one quarter wave length of the desired soundwave in the medium through which the desired signals are transmitted andreceived whereby the index of refraction will be increased.

7. A tank and a sound signaling device located therein, a wall of saidtank being loaded with weights separated from each other, by a distanceapproximately less than one quarter wave length of the desired soundwave,in the medium through which the desired signals are transmitted andreceived whereby the index of refraction of said wall will be madesubstantially the same as water.

8. A tank and a sound signaling device located therein, a wall of saidtank being loaded with weights separated from each other by a distanceapproximately less than one quarter wave length of the desired soundwave in the medium through which the desired signals are transmitted andreceived whereby the index of refraction will be increased.

9. The combination of two electric circuits, two electrically-operatingsound detectors connected to said electric circuits and adapted to causecurrents of varying in- 10. The combination of two electric circuits,two electrically-operating sound detectors connected to said electriccircuits and adapted to cause currents of varying intensity to flow insaid electric circuits upon the receipt of sound waves, indicating meansconnected to said electric circuits adapted to produce an indication onthe receipt of sounds, and means located in said electric circuits,adapted to vary the phase of the varying currents caused to flow by therethe other, and adapted to determine the diceived sounds in each ofsaid circuits rela 65 'tively to the other.

' 11. The combination of two electric circuits, twoelectrically-operating sound detectors connected to said electriccircuits and adapted to cause currents of varying intensity to flow insaid electric circuits upon the receipt of sound waves, indicating meansconnected to said electric circuits adapted to produce an' indication onthe receipt of sounds, and means, comprisin inductances and capacitieslocated in sai electric circuits, adapted to vary the phase of thevarying currents caused to flow by the received sounds in each of saidcircuits relatively to rection from which the sounds are received.

12. A submarine signaling apparatus comprising a liquid container, twosubmarine signaling mechanisms located in the liquid in said container,and means for varying the angle between the line joining the center ,ofsaid two submarine signaling mechanisms and a second line drawn throughthe center of said first line and terminating at opposite sides of saidcontainer.

13. A submarine signaling apparatus comprising a container, a submarinesignaling mechanism located within said container, one wall of saidcontainer being adjacent to the medium through which the signals aresent and received, said wall of said container having its index ofrefraction of sound relative to water substantially the same as that ofthe medium outside the container whereby signals are transmitted andreceived in directions substantially parallel'to the plane of said wallof said container with increased efficiency and loudness.

14. A li uid container, a submarine signaling mec anism located therein,a wall of said container having weights attached thereto, the distancebetween said weights being less than the quarter wave length of thesignals in the liquid, whereby the index of refraction of'sound relativeto water of said wall'may be made to have a desired value.

15. A container, a submarine signaling mechanism located therein, a wallof said container having localized inertia whereby its index ofrefraction of sound relative to water maybe made to have any desiredvalue.

16. A container, a submarine signaling mechanism located therein, a wallof said container having localized inertia whereby its index ofrefraction of sound relative to water is made substantially the same asthat of the medium outside the container throu h which the sounds aresent and recelve REGINALD A. FESSENDEN,

